Friday, December 7, 2007

Data Warehouse Interview-3

What is the difference between Datawarehousing and BusinessIntelligence? Data warehousing deals with all aspects of managing the development, implementation and operation of a data warehouse or data mart including meta data management, data acquisition, data cleansing, data transformation, storage management, data distribution, data archiving, operational reporting, analytical reporting, security management, backup/recovery planning, etc. Business intelligence, on the other hand, is a set of software tools that enable an organization to analyze measurable aspects of their business such as sales performance, profitability, operational efficiency, effectiveness of marketing campaigns, market penetration among certain customer groups, cost trends, anomalies and exceptions, etc. Typically, the term “business intelligence” is used to encompass OLAP, data visualization, data mining and query/reporting tools.Think of the data warehouse as the back office and business intelligence as the entire business including the back office. The business needs the back office on which to function, but the back office without a business to support, makes no sense.

What is the difference between OLAP and datawarehosue?Datawarehouse is the place where the data is stored for analyzingwhere as OLAP is the process of analyzing the data,managing aggregations,partitioning information into cubes for indepth visualization.

What is fact less fact table? where you have used it in your project? Factless table means only the key available in the Fact there is no mesures availalabl

Why Denormalization is promoted in Universe Designing? In a relational data model, for normalization purposes, some lookup tables are not merged as a single table. In a dimensional data modeling(star schema), these tables would be merged as a single table called DIMENSION table for performance and slicing data.Due to this merging of tables into one large Dimension table, it comes out of complex intermediate joins. Dimension tables are directly joined to Fact tables.Though, redundancy of data occurs in DIMENSION table, size of DIMENSION table is 15% only when compared to FACT table. So only Denormalization is promoted in Universe Desinging.

What is the difference between ODS and OLTP? ODS:- It is nothing but a collection of tables created in the Datawarehouse that maintains only current data

where as OLTP maintains the data only for transactions, these are designed for recording daily operations and transactions of a business

What is the difference between datawarehouse and BI? Simply speaking, BI is the capability of analyzing the data of a datawarehouse in advantage of that business. A BI tool analyzes the data of a datawarehouse and to come into some business decision depending on the result of the analysis.